Effects of the growth temperature on the properties of CdTe thin films for solar cell applications

CdTe films for solar cell application were prepared at various growth temperatures by a vacuum evaporation system having close spacing between the source and substrate. The CdTe thin films had a cubic structure highly oriented with the (111) direction perpendicular to the substrate surface, regardless of the growth temperature. The crystallites are of random shape and reach up to about 2 μm in size with increasing growth temperature. The higher growth temperature contributed to the reduction of dark resistivity from 6 × 10⁷ Ω·cm at room temperature to 45.4 × 10⁶ Ω·cm at 300°C. The photovoltaic properties of the CdS/CdTe solar cell were considerably improved with the increase in the growth temperature, which was caused by the increase of (111) texture and grain size in CdTe films.